1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method for reading a patch for tone correction printed by the image processing apparatus and controlling a halftone process in the image processing apparatus in accordance with a result of the reading so as to reduce graininess.
2. Description of the Related Art
In recent years, there is a case where in a screen (parameter for a halftone process) which has been set as a default into an image processing apparatus, a deterioration of graininess becomes conspicuous in association with an aging change or an environmental change and the user calls a service person. In such a case, the service person prints an image sample by the image processing apparatus, confirms the image sample by visual inspection, and if necessary, changes the screen to the screen (parameter for the halftone process) in which the graininess decreases in a service mode of the image processing apparatus.
That is, the service person manually sets the screen setting in which the graininess is small among a plurality of screen settings prepared in the image processing apparatus, thereby coping with such a situation.
Japanese Patent Application Laid-Open No. 2007-208639 discloses a point that graininess is improved in the image processing apparatus.
Japanese Patent Application Laid-Open No. 2004-240112 discloses a point that a focusing situation of an exposure image forming system in an output is discriminated from graininess of an output image and a focus of the exposure image forming system is adjusted based on a result of the discrimination.
As for the graininess, the graininess is corrected through visual inspection of the user or service person in the present situation. That is, in the present situation, if the user or service person is not aware of deterioration in graininess in the image processing apparatus, he cannot change the screen. Since the graininess deteriorates gradually, it is not easy to know a degree of deterioration in graininess as compared with an initial setting and it is difficult to be aware of the graininess deterioration.
According to Japanese Patent Application Laid-Open No. 2007-208639, the graininess is obtained and a screen coefficient in the image processing apparatus is changed. However, when the screen coefficient is changed, the tone differs delicately depending on the screen. Therefore, it is necessary that the sample image is printed by the image processing apparatus by using the changed screen, the tone in the printed image is evaluated, and the tone correction is made again. When the service person changes the screen, it is changed to a screen which is not used so far in the image processing apparatus. Therefore, since the foregoing tone correction has to be also made again, it is troublesome. Naturally, if the screen is manually changed, it is troublesome for the user or service person, a machine stops for such a period of time, and productivity also deteriorates.